I have an extra custom field on cart page. If any user inputs something in that field and updates the cart than I need to add extra 4 Pounds to the cart having label as "Extra Price".

I am using

<checkout_cart_save_after>
    <observers>
        <module_cart_update>
                <type>singleton</type>
                <class>webroot/observer</class>
                <method>logopriceMethod</method>
        </module_cart_update>
    </observers>
</checkout_cart_save_after>

Following is my current code :

public function logopriceMethod(Varien_Event_Observer $observer){
    $invoice = $observer->getEvent()->getInvoice();
    $order = $invoice->getOrder();
    $order->setExtraFeeAmountInvoiced($order->getExtraFeeAmountInvoiced() + 4);
    $order->setBaseExtraFeeAmountInvoiced($order->getExtraFeeAmountInvoiced() + 4);
}

But the above code gives me following error :

Fatal error: Call to a member function getOrder() on null in /var/www/clients/.../Model/Observer.php on line 52

I am using THIS module but it adds custom price as soon as a product is added to cart. What I am trying is to modify the code so as to add extra price on cart update (If there is any value in custom field on cart page).

I have an extra custom field on cart page. If any user inputs something in that field and updates the cart than I need to add extra 4 Pounds to the cart having label as "Extra Price".

I am using

<checkout_cart_save_after>
    <observers>
        <module_cart_update>
                <type>singleton</type>
                <class>webroot/observer</class>
                <method>logopriceMethod</method>
        </module_cart_update>
    </observers>
</checkout_cart_save_after>

Following is my current code :

public function logopriceMethod(Varien_Event_Observer $observer){
    $invoice = $observer->getEvent()->getInvoice();
    $order = $invoice->getOrder();
    $order->setExtraFeeAmountInvoiced($order->getExtraFeeAmountInvoiced() + 4);
    $order->setBaseExtraFeeAmountInvoiced($order->getExtraFeeAmountInvoiced() + 4);
}

But the above code gives me following error :

Fatal error: Call to a member function getOrder() on null in /var/www/clients/.../Model/Observer.php on line 52

I am using THIS module but it adds custom price as soon as a product is added to cart. What I am trying is to modify the code so as to add extra price on cart update (If there is any value in custom field on cart page).

I have an extra custom field on cart page. If any user inputs something in that field and updates the cart than I need to add extra 4 Pounds to the cart having label as "Extra Price".

I am using

<checkout_cart_save_after>
    <observers>
        <module_cart_update>
                <type>singleton</type>
                <class>webroot/observer</class>
                <method>logopriceMethod</method>
        </module_cart_update>
    </observers>
</checkout_cart_save_after>

Following is my current code :

public function logopriceMethod(Varien_Event_Observer $observer){
    $invoice = $observer->getEvent()->getInvoice();
    $order = $invoice->getOrder();
    $order->setExtraFeeAmountInvoiced($order->getExtraFeeAmountInvoiced() + 4);
    $order->setBaseExtraFeeAmountInvoiced($order->getExtraFeeAmountInvoiced() + 4);
}

But the above code gives me following error :

Fatal error: Call to a member function getOrder() on null in /var/www/clients/.../Model/Observer.php on line 52

I have an extra custom field on cart page. If any user inputs something in that field and updates the cart than I need to add extra 4 Pounds to the cart having label as "Extra Price".

I am using

<checkout_cart_save_after>
    <observers>
        <module_cart_update>
                <type>singleton</type>
                <class>webroot/observer</class>
                <method>logopriceMethod</method>
        </module_cart_update>
    </observers>
</checkout_cart_save_after>

Following is my current code :

public function logopriceMethod(Varien_Event_Observer $observer){
    $invoice = $observer->getEvent()->getInvoice();
    $order = $invoice->getOrder();
    $order->setExtraFeeAmountInvoiced($order->getExtraFeeAmountInvoiced() + 4);
    $order->setBaseExtraFeeAmountInvoiced($order->getExtraFeeAmountInvoiced() + 4);
}

But the above code gives me following error :

Fatal error: Call to a member function getOrder() on null in /var/www/clients/.../Model/Observer.php on line 52

I am using THIS module but it adds custom price as soon as a product is added to cart. What I am trying is to modify the code so as to add extra price on cart update (If there is any value in custom field on cart page).